KR20180069046A - Josephson current source systems and methods - Google Patents

Abstract

One embodiment of the present invention describes a Josephson current source system. The system includes a flux-shuttle loop including a plurality of stages arranged in a series loop. Each of the plurality of stages includes at least one Josephson junction. The flux-shuttle loop, when activated, is responsive to an AC clock signal inductively coupled to produce a DC output current provided through the output inductor, about sequentially triggering the at least one Josephson junction in each of the plurality of stages. The system also includes a flux injector system configured to activate the flux-shuttle loop. The flux injector system is further configured to automatically deactivate the flux-shuttle loop in response to the amplitude of the DC output current increasing to a predetermined deactivation threshold.

Description

Josephson current source systems and methods

The present invention relates generally to quantum and classical digital superconducting circuits, and more specifically to Josephson current source systems and methods.

The present application claims priority from U.S. Patent Application No. 14/943671, filed on November 17, 2015, the entire contents of which are incorporated herein by reference.

Superconducting digital technology provides computing and / or communication resources with the advantages of unprecedented high speed, low power dissipation and low operating temperature. Superconducting digital technology has evolved as an alternative to CMOS technology and includes superconductors based on a single flux quantum superconducting circuit typically utilizing Josephson junctions and has a 20 Gb / ) Or at typical data rates greater than that, it can exhibit typical signal power dissipation of less than 1 nW (nanowatts) per active device and can operate at a temperature of about 4 Kelvin. Certain superconducting circuits in which Josephson junctions are active devices may require DC current bias of the Josephson junctions. Typical systems can use the bias resistance network directly to provide the bias current, which can generate heat resulting from spurious magnetic fields and high power dissipation. The power budget in these circuits may be dictated by the static power consumption, which may be lost in the bias resistor network, regardless of whether the active device is switching or not.

One embodiment of the present invention describes a Josephson current source system. The system includes a flux-shuttle loop including a plurality of stages arranged in a series loop. Each of the plurality of stages includes at least one Josephson junction. The flux-shuttle loop, when activated, is configured to generate a DC output current through an output inductor, wherein the AC-clock signal is inductively coupled to generate a DC output current through the output inductor, ) May be configured to sequentially trigger Josephson junctions in each of the plurality of stages. The system also includes a flux injector system configured to activate the flux-shuttle loop. The flux injector system is further configured to automatically deactivate the flux-shuttle loop in response to an amplitude of the DC output current increasing to a predetermined deactivation threshold.

Another embodiment of the present invention includes a method for generating a DC output current. The method includes providing an AC clock signal through a primary inductor of a clock transformer. The clock converter includes a secondary inductor arranged in a loop with at least two of the plurality of stages of the flux-shuttle loop. The plurality of stages may be arranged in a series sequential loop. The method further includes providing a DC injection signal to a flux injector system to generate a single flux quantum (SFQ) pulse at one of the plurality of stages. The SFQ pulse may be propogated through the plurality of stages to produce voltage pulses in the output inductor to produce a DC output current based on sequential triggering of the Josephson junction in each of the plurality of stages. The flux injector system may be configured to automatically deactivate and reactivate the flux-shuttle loop based on the amplitude of the DC output current with respect to the amplitude of the DC injection signal.

Another embodiment of the present invention describes a flux-shuttle loop comprising a first stage, a second stage, a third stage and a fourth stage arranged in a series loop. Each of the first stage, the second stage, the third stage, and the fourth stage includes at least one Josephson junction. The flux-shuttle loop, when activated, causes the first stage, the second stage, the third stage and the fourth stage around the flux-shuttle loop in response to an inductively coupled AC clock signal, And the AC clock signal comprises a quasi-phase component and a quadrature-phase component that are out of phase by about 90 degrees. The system also includes a first storage inductor configured to receive a current step associated with the sequential triggering of Josephson junctions associated with the first stage and the third stage and in each of the first stage and the third stage do. The system also includes a second storage inductor configured to receive a current step associated with the sequential triggering of the Josephson junction in the second stage and in the fourth stage and in each of the second and fourth stages do. The system also includes an output coupled to each of the first storage inductor and the second storage inductor and configured to provide a DC output current in response to a current step provided through the first storage inductor and the second storage inductor, And an inductor. The system further comprises a flux injector system configured to activate the flux-shuttle loop and to be further configured to automatically deactivate and reactivate the flux-shuttle loop based on the amplitude of the DC output current.

1 shows an example of a superconducting circuit system.
2 shows an example of a Josephson current source circuit.
3 shows an example of a timing diagram.
4 shows an example of a flux injector system.
5 shows an example of a flux diagram.
6 shows an example of a method for generating a DC output current.

The present invention relates generally to quantum and classical digital superconducting circuits, and more particularly to Josephson current source systems and methods. The Josephson current source includes a flux-shuttle loop including a plurality of stages arranged in a series loop. Each of the stages may be arranged as a superconducting quantum interference device (SQUID) and thus comprises at least one Josephson junction. The Josephson current source also includes a set of bias converters and clock converters, a set of storage inductors, each associated with at least one of the stages, and an output inductor configured to provide a DC output current. The clock converters are configured to inductively couple (or connect) the AC clock signal to the flux-shuttle loop, such that the AC clock signal is coupled to a bias current in a flux-shuttle loop to provide. The Josephson current source also includes a flux injector system. For example, at initialization, the flux-shuttle loop is activated based on a single flux quantum (SFQ) pulse that propogates through each of the about stages of the flux-shuttle loop. The flux injector system may be configured to inject the SFQ pulse. Thus, when the flux-shuttle is activated, the Josephson junction (s) in each of the stages sequentially propagates the SFQ pulse around the flux-shuttle loop based on the frequency of the AC clock signal . For example, the SFQ pulse may propagate through a given stage in a positive or negative cycle czycle of the AC clock signal. The SFQ pulse may be provided to a storage inductor associated with the respective stage to provide a current step to the output inductor in response to a voltage pulse generated at each stage such that the output inductor is coupled to the AC clock And provides the DC output current based on voltage pulses provided from each stage in each of the positive and negative cycles of the signal.

For example, the AC clock signal may be an orthogonal clock signal comprising an in-phase portion and a quadrature-phase portion, and the flux-shuttle loop may include four stages. The primary inductor of the first clock converter is capable of propagating the in-phase portion of the AC clock signal, and the secondary inductor of the first clock converter is coupled with the first and third stages Can be arranged in series. Similarly, the primary inductor of the second clock converter is capable of propagating the quadrature-phase portion of the AC clock signal, and the secondary inductor of the second clock converter is arranged in series with the second and fourth stages . Thus, the first stage and the second stage are each responsive to SFQ pulses propagating in a first cycle (e.g., a positive cycle) of a quadrature-phase component of the AC clock signal and a quasi-phase component of the AC clock signal, Phase component of the AC clock signal and a second cycle (e.g., a negative cycle) of the quadrature-phase component of the AC clock signal, respectively, from the first flux state to the second flux state via the clock converter and the second clock converter, And is reset from the second flux state to the first flux state in response to each SFQ pulse propagated in each of the first and second flux states. Similarly, the third stage and the fourth stage are each responsive to SFQ pulses propagating in each of the co-phase component of the AC clock signal and the second cycle of the quadrature-phase component, Phase component of the AC clock signal and the SFQs propagating in the first cycle of the quadrature-phase component, respectively, from the second flux state to the first flux state via the second clock converter, And is reset from the first flux state to the second flux state in response to each pulse.

In addition, the flux injector system is configured to automatically deactivate and reactivate the flux-shuttle loop based on the amplitude of the DC output current. For example, the flux injector system may form part of the first stage and receive a DC injection signal inductively coupled to the flux injector system. Thus, the DC injection signal can generate an injection current in the flux injector system, and the injection current includes an amplitude that can set an activation threshold and an inactivation threshold for the DC output signal. For example, the DC output signal may be inductively coupled to the flux injector system to provide a feedback current having a current direction opposite to the injection current. Thus, in response to the feedback current, in response to the DC output current increasing above the deactivation threshold, the first stage is configured to control the respective Josephson junctions < RTI ID = 0.0 >Lt; RTI ID = 0.0 > flux-shuttle loop, < / RTI > Thus, the flux-shuttle loop maintains a deactivated quiescent state that consumes approximately zero power. When the DC output current decreases below an activation threshold, such as in response to being consumed by associated circuit devices, the flux in the first stage is increased enough to trigger the respective Josephson junction, The flux-shuttle loop is automatically reactivated so that the DC output current begins to increase. Thus, the Josephson current source can autonomously activate and deactivate to meet current consumption requirements in a more efficient manner.

Fig. 1 shows an example of a superconducting circuit system 10. Fig. For example, the superconducting circuit system 10 may be implemented in any of a variety of classical and quantum computing applications, such as memory or processing systems. The superconducting circuit system 10 includes a device 12 that receives the DC output current, shown in FIG. 1, as the DC output current I _OUT . For example, the DC output current I _OUT may be provided as a driver signal for driving the device 12. For example, the device 12 may correspond to a memory driver such as to provide a read current or a write current to a memory cell.

The superconducting circuit system 10 also includes a Josephson current source 14 configured to generate a DC output current I _OUT in response to an AC clock signal CLK and the AC clock signal CLK is coupled to a Josephson current source 14, Lt; / RTI > For example, the clock signal CLK may have a substantially constant frequency (e.g., about 5 GHz or 10 GHz) and an AC current amplitude (e.g., about 10 GHz), such as applicable to reciprocal quantum logic (RQL) a sinusoidal waveform having a magnitude (e.g., about 2 mA RMS). The Josephson current source 14 is shown as receiving a DC injection signal INJ and the DC injection signal INJ is coupled to the Josephson current source 14 to activate the Josephson current source 14 to produce a DC output current I _OUT . ). ≪ / RTI > The DC injection signal INJ can set a magnitude for at least one threshold for automatic deactivation and reactivation of the Josephson current source 14. In addition,

In the example of Figure 1, the Josephson current source 14 includes a flux-shuttle loop 16. The flux-shuttle loop 16 is configured to propagate a single-flux quantum pulse (i.e., fluxon) around the flux-shuttle loop 16 based on the frequency of the clock signal CLK And may comprise a plurality of stages configured. As described herein, the term "propagate " for the SFQ pulse describes an SFQ pulse that is generated through triggering of a Josephson junction in a given stage of a flux-shuttle loop, The voltage of the SFQ pulse, combined with the bias voltage (e.g., via the clock signal (CLK)), causes the Josephson junction of the next stage of the flux-shuttle loop to generate another SFQ pulse, ≪ / RTI > The term "loop" for the flux-shuttle loop 16, as described herein, refers to a substantially continuous loop of stages of the flux-shuttle loop (e.g., Circular)) array. Therefore, when the flux-shuttle loop 16 is activated, the SFQ pulses can propagate substantially continuously around the flux-shuttle loop 16. Further, as described herein, the term "propagation around the flux-shuttle loop" for the SFQ pulse is defined as the propagation of the SFQ pulse at a given phase of the AC clock signal CLK at each of the stages of the flux- Shuttle loop 16 so that the SFQ pulses generated in one stage propagate to the next stage to generate another SFQ pulse so that the SFQ pulses propagate from one stage to the next in a sequential manner. Lt; RTI ID = 0.0 > SFQ < / RTI >

For example, the Josephson current source 14 may also include a set of bias converters and clock converters, a set of storage inductors and a DC output current I _OUT , each associated with at least one of the stages of the flux-shuttle loop 16 / RTI > The clock converters are configured to inductively couple the AC clock signal CLK to the flux-shuttle loop 16 such that the AC clock signal CLK provides a bias current in the flux-shuttle loop 16. The Josephson current source 14 also includes a flux injector system 18. For example, at initialization, the flux injector system 18 may inject the SFQ pulses to activate the flux-shuttle loop 16 based on the SFQ pulses propagating through each of the stages around the flux-shuttle loop 16 Lt; / RTI > Thus, when the flux-shuttle loop 16 is activated, the Josephson junction (s) of each of the stages will propagate the SFQ pulse around the flux-shuttle loop 16 based on the frequency of the AC clock signal CLK Trigger. For example, the SFQ pulse may propagate through a given stage in each positive or each negative cycle of the AC clock signal CLK. The SFQ pulse is generated to provide a current step to the output inductor such that the output inductor provides the DC output current based on voltage pulses provided from each stage in each positive and negative cycles of the AC clock signal Lt; RTI ID = 0.0 > storage < / RTI > Therefore, the DC output current I _OUT can flow through the output inductor based on the current steps sequentially provided to the output inductor based on the frequency of the clock signal CLK. For example, the current step are, the resulting voltage (resulting voltage) pulses to integrate (integrate) in the output inductor to provide a DC output current (I _OUT), a voltage to the storage inductor, respectively (e. G. Gt; / 2 < / RTI > GHz).

In addition, the flux injector system 18 includes a feedback control mechanism 20 configured to automatically deactivate and reactivate the flux-shuttle loop 16 based on the amplitude of the DC output current I _OUT . As an example, the flux injector system 18 may form part of the first stage of the flux-shuttle loop 16. For example, each of the flux injector system 18 is the flux injector system 18 in order to provide a feedback current and the injection current has a current direction opposite to each, DC output current (I _OUT) and a DC injection signal (INJ) Inductive coupling. Thus, in response to the feedback current, and thus in response to a DC output current I _OUT that increases above the deactivation threshold, the first stage of the flux-shuttle loop 16 is coupled to the flux- Has less flux than is sufficient to trigger each Josephson junction to sustain the propagation of the SFQ pulse, thus automatically deactivating the flux-shuttle loop 16. Thus, the flux-shuttle loop 16 maintains a deactivated dormant state consuming approximately zero power. When the DC output current I _OUT decreases below the activation threshold, such as in response to being consumed by the circuit device 12, the flux of the first stage of the flux-shuttle loop 16, And thus automatically reactivates the flux-shuttle loop so that the DC output current I _OUT begins to increase. Therefore, the Josephson current source 14 can operate to generate the DC output current I _OUT in a power efficient manner. As an example, the Josephson current source 14 may not produce substantially any heat from a static power dissipation, as opposed to typical resistance-based DC current sources. Thus, the Josephson current source 14 is capable of generating a DC output current < Desc / Clms Page number 10 > current sufficiently high to satisfy the current bias requirements of the circuit device 12, especially in quantum computing and energy-efficient high- Based on the automatic deactivation of the flux injector system 18 in response to the current I _OUT , can operate more efficiently and more effectively than typical current sources. In addition, as described in more detail herein, the amplitude of the DC injection signal INJ can set at least one of the activation and deactivation thresholds for automatic deactivation and reactivation of the flux-shuttle loop 16. [

Fig. 2 shows an example of the Josephson current source circuit 50. Fig. The Josephson current source circuit 50 may correspond to the Josephson current source 14 of the superconducting circuit system 10. The Josephson current source circuit 50 therefore includes a plurality of stages shown in the example of Figure 2 as first stage 54, second stage 56, third stage 58 and fourth stage 60 And a flux-shuttle loop 52. The flux- The stages 54,56, 58 and 60 are sequentially coupled to form a series loop arrangement. Josephson current source circuit 50 is configured to generate a DC output current based on the AC clock signal. In the example of FIG. 2, the AC clock signal is shown as a quadrature clock signal comprising a co-phase component (CLK _I ) and a quadrature-phase component (CLK _Q ). As an example, the co-phase component (CLK _I ) and the quadrature-phase component (CLK _Q ) may correspond to an AC clock signal that can be implemented for RQL circuits collectively. The DC output current is shown as current (I _OUT ) flowing through the output inductor (L _OUT ).

Each of the stages 54, 56, 58, and 60 is configured in a substantially SQUID arrangement, and the stages 56, 58, and 60 are substantially similar to each other. In the example of Figure 2, the first stage 54 includes a first Josephson junction (J _{1_1),} the second Josephson junction (J _{2_1),} the inductor (L _{X_1)} and the inductor (L _{Y_1).} The second stage 56 includes a first Josephson junction J _{1_2} , a second Josephson junction J _{2_2} , an inductor L _{X_2} , and an inductor L _{Y_2} . The third stage 58 comprises a first Josephson junction (J _{1_3),} the second Josephson junction (J _{2_3),} the inductor (L _{X_3)} and an inductor (L _{Y_3).} Claim 4 The stage 60 comprises a first Josephson junction (J _{1_4),} the second Josephson junction (J _{2_4),} the inductor (L _{X_4)} and an inductor (L _{Y_4).} In addition, the Josephson current source 50 is configured to inject SFQ pulses into the flux-shuttle loop 52 during initialization and to inject the SFQ pulses into the flux injector < RTI ID = 0.0 > System 62 shown in FIG. For example, the flux injector system 62 may have a different self-series inductance than the other stages 56, 58 and 60. The first stage 54 is separated from the second stage 56 by the inductor (L _{I_2),} the second stage 56 and third stage 58 are separated by an inductor (L _{I_3).} The third stage 58 and the fourth stage 60 are separated by an inductor L _{I_4} and the fourth stage 60 is separated from the first stage 54 by an inductor L _{I_1} . Therefore, the SFQ pulse generated by the flux injector system 62 can circulate through the flux-shuttle loop 52 within the loop formed by the stages 54, 56, 58,

Josephson current source 50 also includes a pair of clock converters, each of which is associated with a pair of stages 54, 56, 58 and 60. 2, the clock converters include a first clock converter T ₁ associated with the first stage 54 and the third stage 58 and a second clock converter T ₁ associated with the second stage 56 and fourth stage 60 And a second clock converter (T ₂ ). In addition, the Josephson current source 50 also includes a first bias transformer T _B1 associated with the first stage 54 and the third stage 58, as well as a first bias converter T _B1 associated with the second stage 56 and fourth stage 60, And a second bias converter T _B2 .

Clock converter (T ₁₎ is in-phase component (CLK _I) comprises a first inductor (L _{1_1)} flows, and a clock converter (T ₂₎ are orthogonal-phase component (CLK _Q) flows the primary inductor (L _{1_2} ). In addition, the bias converters T _B1 and T _B2 include respective primary inductors L _{B_1} and L _{B_3} through which the DC bias signal BIAS flows. Clock converter (T ₁₎ is a (e. G., Inductors (L _{X_1} and L _{Y_1)} and the coupling between the inductor (L _{X_3} and L _{Y_3))} a first bias transformer (T _B1) 2 primary inductor (L _{B_2} of Phase component CLK _I through a secondary inductor L 2 _{_} 1 arranged in series with the flux injector system 62 (for example, as described in more detail herein) To the first stage 54 and to the third stage 58. Similarly, the clock converter T ₂ is coupled to the secondary inductor T _{B2 of} the second bias converter T _B2 (e.g., coupled between the inductors L _{X_2} and L _{Y_2} and the inductors L _{X_4} and L _{Y_4} ) Phase component CLK _Q to the second stage 56 and the fourth stage 60 via a second inductor L _{2_2} arranged in series with the second inductor L _{B_4} . The secondary inductors L _{1_2} and L _{B_2 of} each of the transducers T ₁ and T _B1 thus form a first loop 64 between the first stage 54 and the third stage 58 . In a similar manner, the secondary inductors L _{2_2} and L _{B_4 of} each of the transducers T ₂ and T _B2 are _coupled to a second loop 66 between the second stage 56 and the fourth stage 60 .

As an example. Each of the co-phase component CLK _I and the quadrature-phase component CLK _Q may comprise a positive portion (e.g., in the first half of each cycle) and a negative portion (e.g., in the second half of each cycle) have. Based on the arrangement of the clock converters (T ₁ and T ₂ ) for each of the stages 54, 56, 58 and 60, the flux state of the stages 54, 56, 58 and 60, Can be sequentially switched in response to the SFQ propagating in each phase and in each of the opposite phases of the quadrature-phase component (CLK _I ) and the quadrature-phase component (CLK _Q ) and around the flux-shuttle loop. For example, each of the co-phase component CLK _I and the quadrature-phase component CLK _Q may have a first phase corresponding to a positive peak (e.g., in the first half of each period) A second phase that is opposite to the first phase, and therefore corresponds to a negative peak. Thus, the flux-shuttle loop 52 is able to track the flux state of the secondary inductors L _{B_2} and L _{B_4} of the bias converters T _B1 and T _B2 , thus allowing the flux-shuttle loop 52 56, 58, and 58 through alternating first and second phases of a co-phase component (CLK _I ) and a quadrature-phase component (CLK _Q ) 60 can be tracked.

In addition, the Josephson current source 50 includes a first storage inductor L _{S_1} and a flux injector system 62 and a second loop 66 interconnecting the flux injector system 62 and the first loop 64, to a second storage inductor (L _{S_2)} for connecting to each other. The output inductor L _OUT conducts the output current I _OUT through the injector system 62 from each of the storage inductors L _{S_1} and L _{S_2} . In response to the SFQ pulses being sequentially propagated through each of the stages 54, 56, 58 and 60, a current step is generated in each of the storage inductors L _{S_1} and L _{S_2} . In response to the triggering of each Josephson junction in the first stage 54 and the third stage 58 in response to the switching of the flux states of each of the first stage 54 and the third stage 58, The SFQ pulse generates a resulting current step in the storage inductor L _{S_1} . Similarly, in response to triggering of each Josephson junction in the second stage 56 and fourth stage 60 in response to switching of the flux states of each of the second stage 56 and the fourth stage 60, and it generates the current step SFQ pulses result from the storage inductor (L _{S_2).} As a result, the Josephson current source 50 is a DC signal source working (act), the output inductor (L _OUT) that is provided through the storage inductor (L _{S_1} and L _{S_2)} for providing an output current (I _OUT) Integrate each of the current steps. As a result, the output current (I _OUT), the in-phase component (CLK _I) and quadrature-as a DC signal converted from a phase component (CLK _Q), circuit devices (e.g., of an example of the first circuit device 12 ). ≪ / RTI >

Fig. 3 shows an example of the timing diagram 100. Fig. The timing diagram 100 includes a co-phase component (CLK _I ) and a quadrature-phase component (CLK _Q ), as indicated by legend 102 as a function of time. Each of the co-phase component (CLK _I ) and the quadrature-phase component (CLK _Q ) is shown as sine signals centered around 0 with magnitudes. Copper in the example of FIG. 3-phase component (CLK _I) and quadrature - can correspond to the phase component (CLK _Q) - phase component (CLK _I) and quadrature-phase component (CLK _Q) is the same in the example of Figure 2, have. Therefore, in the following description of the example of Fig. 3, the example of Fig. 2 is referred to.

The flux-shuttle loop 52 may be activated through the flux injector system 62, as will be described in greater detail herein. When activated, at time t ₀ , the positive portion of the co-phase component CLK _I begins and a positive peak of the co-phase component CLK _I occurs at a time t ₁ . Therefore, the in-phase component (CLK _I) starts to induce a current through the secondary inductor (L _{2_1)} based on inductive coupling between the first inductor (L _{1_1).} The magnitude of the current is combined with the SFQ pulse and the bias current at a time immediately preceding the time t ₁ (e.g., based on the inductance of the transducer T ₁ ) and the SFQ pulse is coupled to the inductor (From the fourth stage 60 via L _{I_1} ), or from the flux injector system 62 upon activation, provided by the Josephson junction J _{2_} 4, and the bias current is derived from the inductance of the primary inductor L _{B_1 And} is provided through the secondary inductor L _{B -} 2 based on the coupling. Therefore, the trigger for the Josephson junction critical current (critical current) has to be greater than the Josephson junction (J _{1_1} and _{2_1} J) (or just a Josephson junction (J _{2_1)} at initialization) the (J _{1_1} and _{2_1} J). As a result, Josephson junctions J 1 _{_ 1} and J 2 _{_ 1} propagate the SFQ pulse, and the SFQ pulse is added to the output inductor L _OUT to increase the amplitude of the DC output current I _OUT 1 Provide voltage pulses to the storage inductor (L _{S_1} ). The SFQ pulse then propagates to the second stage 56.

In addition, the time (t ₁₎ in the orthogonal-phase occurs in the component _(Q CLK), the time (t ₂₎ of the positive peak-phase component _(Q CLK) and start of the positive portion, perpendicular. Therefore, the quadrature-phase component (CLK _Q ) begins to derive the current through the secondary inductor (L 2 _{_} 2) based on the inductive coupling with the primary inductor (L 1 _{_} 2). Time (t ₂₎ immediately before the time (e.g., a converter (T ₂ on the basis of the inductance of a)), the amplitude (magnitude) of the current (L SFQ pulses and the first inductor provided by the Josephson junction (J _{2_1) B_2} based on the inductive coupling with the bias current supplied through the secondary inductor L _{B_4} . Therefore, the threshold current of the Josephson junctions ( _{J1_2} and _{J2_2} ) is exceeded and triggers the Josephson junction ( _{J2_2} ). As a result, the Josephson junctions J _{1_2} and J _{2_2} propagate the SFQ pulse, and the SFQ pulse is applied to the storage integrated by the output inductor L _OUT to increase the amplitude of the DC output current I _OUT And generates a current step in the inductor L _{S_2} . The SFQ pulse then propagates to the third stage 58.

Also, at time (t _2), copper-section of the negative phase component (CLK _I) is started, and copper-phase component of the negative peak (CLK _I) occurs at a time (t _3). Therefore, the in-phase component (CLK _I) starts to induce a current through the secondary inductor (L _{2_1)} based on inductive coupling between the first inductor (L _{1_1).} In the immediately preceding time period (t _3), the amplitude (magniutde) of the current is coupled to the bias current provided through the SFQ pulses and a secondary inductor (L _{B_2)} that is propagated by the Josephson junction (J _{2_2).} Therefore, the critical current of the Josephson junction (J and J _{1_3 2_3)} is exceeded triggers the Josephson junction (J _{1_3} and _{2_3} J). As a result, the Josephson junction of the (J _{1_3} and J _{2_3)} is storage propagating the SFQ pulse, said SFQ pulse is to increase the amplitude of the DC output current (I _OUT), integrated by the output inductor (L _OUT) And generates a current step in the inductor L _{S_1} . The SFQ pulse then propagates to the fourth stage 60.

In addition, the time (t ₃₎ in an orthogonal - occurs in phase component _(Q CLK) negative peak, the time (t ₄₎ in-phase component _(Q CLK) of the negative portion starts, and orthogonal. Therefore, the quadrature-phase component (CLK _Q ) begins to derive the current through the secondary inductor (L _{2_4} ) based on the inductive coupling with the primary inductor (L _{1_4} ). In the immediately preceding time period (t _4), the amplitude (magnitude) of the current is coupled to the bias current provided through the SFQ pulses and a secondary inductor (L _{B_4)} that is propagated by the Josephson junction (J _{2_3).} Therefore, the critical current of the Josephson junction (J and J _{1_4 2_4)} is exceeded triggers the Josephson junction (J _{1_4} and _{2_4} J). As a result, Josephson junctions _{J1_4} and _{J1_4} J _{2_4} propagates the SFQ pulse and the SFQ pulse changes the current step in the storage inductor L _{S_2} integrated by the output inductor L _OUT to increase the amplitude of the DC output current I _OUT . The SFQ pulse then propagates back to the first stage 54 to trigger the Josephson junction (J 1 _{_} 1).

Also, at time (t _4), the same-phase component of the positive part (CLK _I) is started. Therefore, as previously described, the process of transforming the in-phase component (CLK _I ) and the quadrature-phase component (CLK _Q ) is repeated such that the time (t ₄ ) is equal to the time (t ₀ ). In this way, the flux-shuttle loop 52 is in, the Josephson junction while they are activated through the flux injector system (62) (J _{1_1,} J _{2_1,} J _{1_2,} J _{2_2,} J _{1_3,} J _{2_3,} J _{1_4} and J _{2_4} may be sequentially triggered based on changes in the flux states of the first loop 64 and the second loop 66 so that the corresponding stages 54,56, 58 and 60 are sequentially Can be triggered. Thus, the SFQ pulse is, in-phase component (CLK _I) and quadrature-phase component of the Josephson based on the frequency of the (CLK _Q) junction, respectively in response to the triggering of the _{(J 2_1, J 2_2, J} 2_3 and J _{2_4)} Shuttle loop 52 to continue to provide voltage pulses to the output inductor L _OUT . As a result, the output inductor (I _OUT ) can integrate the voltage pulses to increase the amplitude of the DC output current (I _OUT ).

4 shows an example of a flux injector system 150. [ The flux injector system 150 is configured to automatically activate (e.g., reactivate) and deactivate the associated flux-shuttle loop. The flux injector system 150 may correspond to the exemplary flux injector system 18 of FIG. 1 and / or the exemplary flux injector system 62 of FIG. Therefore, in the following description of the example of Fig. 4, the examples of Figs. 1 to 3 are referred to.

The flux injector system 150 is shown as the forming part of the first stage 54 between the inductors L _{X_1} and L _{Y_1} . Flux injector system 150 includes a first transducer 152 including a primary inductor L _DC receiving a DC injection signal INJ and a secondary inductor L _INJ providing an induced injection current I _INJ . ). The flux injector system 150 also includes a second inductor L _FB that includes a primary inductor L _PO that receives the DC output current I _OUT and a secondary inductor L _FB that provides an induced feedback current I _FB , (154). The secondary inductors L _INJ and L _FB are interconnected by a node 156 coupled to the secondary inductor L _{B_2} of the first bias converter T _B1 and the inductors L _{X_1} and L L with a Josephson junction (J _INJ) disposed between _{Y_1)} is arranged in the loop (158). 4, the feedback current I _FB and the injection current I _INJ have opposite current directions so that activation and deactivation of the Josephson current source 50 is controlled by the feedback current I _FB and the injection current I _INJ ), ≪ / RTI >

The DC injection signal INJ is applied to the primary inductor L _DC of the converter 152 to provide the induced injection current I _INJ when the initialization (e.g., the amplitude of the DC output current I _OUT is approximately zero) ). ≪ / RTI > The net current flow in the loop 158 is entirely defined by the injection current I _INJ since the amplitude of the DC output current I _OUT at the time of initialization is approximately zero and the injection current I _INJ is defined by the flux - Provide sufficient flux of loop 158 to trigger Josephson junction (J _INJ ) to inject SFQ pulses into shuttle loop 52. Therefore, the SFQ pulse can be cycled through the flux-shuttle loop 52 according to the manner previously described in the examples of FIGS. 2-3. While the SFQ pulse continues to propagate around the flux-shuttle loop 52, the DC output current I _OUT increases and thus the amplitude of the feedback current I _{FB also} increases. As a result, the amplitude of the feedback current I _FB is subtracted from the injection current I _INJ for the flux of the loop 158, thereby reducing the flux of the loop 158. When the DC output current I _OUT increases to a predetermined deactivation threshold that can be defined by the amplitude of the DC injection signal INJ and thus the injection current I _INJ , Triggering of the Josephson junction (J _INJ ) by generating a negative SFQ pulse (i.e., anti-fluxon) in the first phase of the clock signal CLK _I. As a result, the junction J _INJ may be untriggered to cancel the SFQ pulse so that the SFQ pulse stops propagating around the flux-shuttle loop 52, The amplitude of the output current I _OUT can be maintained at a substantially constant amplitude. Therefore, the flux injector system 150 can automatically deactivate the Josephson current source 50 based on the amplitude of the DC output current I _OUT .

In response to a decrease in the amplitude of the DC output current I _OUT , as the net current flow in the loop 158 increases, such as in response to the DC output current I _DC being consumed by the circuit device 12, The flux of the fuel 158 begins to increase. When the DC output current I _OUT decreases to a predetermined activation threshold - likewise, as defined by the amplitude of the DC injection signal INJ and thus the injection current I _INJ - the flux of the loop 158 is May be increased in an amount sufficient to trigger the Josephson junction (J _INJ ), thus re-injecting the SFQ pulse into the flux-shuttle loop 52. Accordingly, the SFQ pulse can be cycled back through the flux-shuttle loop 52 to increase the DC output current I _DC . Therefore, the flux injector system 150 can automatically reactivate the Josephson current source 50 based on the amplitude of the DC output current I _OUT .

FIG. 5 shows an example of the flux diagram 200. FIG. The flux diagram 200 may correspond to the operation of the flux injector system 150. 5, the flux diagram 200 is a plot of the superconducting phase ("PHASE") of the Josephson junction J _INJ relative to the flux ("FLUX"Lt; / RTI > Therefore, in the following description of the example of Fig. 5, the examples of Figs. 2 to 4 are referred to.

The flux diagram 200 is responsive to the applied current I _INJ at a first point corresponding to the state at the completion of the initialization of the Josephson current source 50 and therefore at a DC output current I _OUT of approximately zero 202, respectively. At a first point 202, the DC injection signal INJ may be provided through the primary inductor L _DC of the transducer 152 to provide an induced injection current I _INJ . Since the amplitude is substantially zero in the DC output current (I _OUT) at initialization, net current flow is defined entirely by the injection current (I _INJ), the injection current (I _INJ) in the loop 158 is Φ to the loop 158 _{INJ and} the magnetic flux of? _INJ may be sufficient to trigger the Josephson junction (J _INJ ) to inject the SFQ pulse into the flux-shuttle loop 52. Therefore, the flux-shuttle loop 52 can be activated to cycle the SFQ pulse through the flux-shuttle loop 52 according to the manner previously described in the examples of FIGS. 2-3.

While the SFQ pulse continues to propagate around the flux-shuttle loop 52, the DC output current I _OUT increases and thus also the amplitude of the feedback current I _FB increases. As a result, the amplitude of the feedback current I _FB is subtracted from the injection current I _INJ with respect to the flux of the loop 158, and thus the flux of the loop 158 decreases, as indicated by the arrow 204, do. Flux of the DC output current (I _OUT) is DC injection signal (INJ) amplitude, and thus to increase to a predetermined disable threshold, which may be defined by the injection current (I _INJ), the loop 158 of the flux (Φ _OFF To the point 206 corresponding to the point of interest. Flux (Φ _OFF) is the same - providing an anti-triggered and thus the negative SFQ pulses of the Josephson junction (J _INJ) to clear the SFQ pulses supplied from the first phase Josephson junction (J _{1_1)} in the phase component (CLK _I) , And thus fails to trigger Josephson junction J 2 _{_} 1. Therefore, anti-triggering of Josephson junction (J _INJ ) causes a decrease in phase from point 206 to point 210, as indicated by arrow 208. Thus, the flux-shuttle loop 52 is automatically deactivated, so that the SFQ pulse stops propagating around the flux-shuttle loop 52, and thus the amplitude of the DC output current I _OUT is stopped State at a substantially constant amplitude.

The net current flow in the loop 158 increases in response to a decrease in the amplitude of the DC output current I _OUT as the DC output current I _OUT is consumed by the circuit device 12, 212, the flux of the loop 158 begins to increase. Flux (Φ _ON) in response to the flux to increase to point 214, the flux is a predetermined activation threshold of the loop (158) corresponding to the - amplitude and therefore the injection current (I _INJ) in the same manner, DC injection signal (INJ) Lt; RTI ID = 0.0 > as < / RTI > Therefore, the flux (Φ _ON) may correspond to a flux of sufficient loop 158 to trigger a Josephson junction (J _INJ), therefore the phase points, the Josephson junction (J _INJ), as shown by arrow 216 Lt; RTI ID = 0.0 > 214 < / RTI > As a result, the SFQ pulse is re-injected into the flux-shuttle loop 52. Therefore, the SFQ pulse may be cycled back through the flux-shuttle loop 52 to increase the DC output current I _OUT . Thus, since the flux diagram 200 is related to the activation and deactivation of the Josephson junction J _INJ and thus the flux-shuttle loop 52 based on the amplitude of the DC output current I _OUT , the flux diagram 200 ) Shows the circulation pattern of the flux of the loop 158. [

In the example of FIG. 5, the fluxes PHI _ON and PHI _OFF are dependent on the ratio of the inductance of the Josephson junction (J _INJ ) and the loop 158, and are therefore substantially fixed. The flux? _INJ depends on the relative amplitudes of the injection current I _INJ and the feedback current I _FB and therefore depends on the amplitude of the DC injection signal INJ and the amplitude of the DC output current I _OUT , respectively. The feedback current I _FB affects the total flux of the loop 158 and depends on the DC injection signal INJ in relation to the fluxes? _ON and? _OFF . Therefore, the amplitude of the output current (I _OUT) is the total flux in the loop 158, the flux (Φ _ON) increased sikineunde or the total flux in the loop 158, the flux feedback necessary sikineunde reduced to (Φ _OFF), current is (I _FB < / RTI > Thus, the amplitude of the DC injection signal INJ defines the amplitude of the feedback current I _FB required to achieve a total loop flux of? _ON or? _OFF for the loop 158. Therefore, the amplitude of the DC injection signal INJ may be set to define at least one of the predetermined activation and deactivation thresholds for the Josephson current source 50. [

In view of the above-described structural and functional structures, the method according to various aspects of the present invention can be better understood with reference to Fig. 6 are shown and described as being performed sequentially, some aspects of the present invention may be implemented in accordance with the present invention in different orders than those shown and described herein and / It is to be understood that the invention is not limited by the order set forth, as it may occur concurrently with other aspects shown and described herein. Moreover, not all illustrated features may be required to implement a methodology in accordance with aspects of the present invention.

6 shows an example of a method 250 for generating a DC output current (e.g., DC output current I _OUT ). At 252, an AC clock signal (e.g., an AC clock signal CLK) is coupled to the primary inductors (e.g., primary inductors L 1 _{_ 1} and L 2 _{_} 1) of each clock converter (eg, clock converters T ₁ and T ₂ ) _{1_2} ). The clock converter is coupled to at least two stages of a plurality of stages (e.g., stages 54,56, 58 and 60) of a flux-shuttle loop (e.g., flux-shuttle loop 52) the second inductor are arranged in a loop (64 and 66)) (e.g., the second inductor (L L _{2_1} and _{2_2)} may comprise a). The plurality of stages may be arranged in a serial sequential loop. At 254, a DC injection signal (e.g., a DC injection signal INJ) is provided to the flux injector system (e.g., the flux injector system 62) to generate SFQ pulses at one of the plurality of stages. The SFQ pulse is the Josephson junction (e.g., Josephson junction in (J _{2_1,} J _{2_2,} J _{2_3} and J _{2_4))} output to the basis of the sequential triggering generating the DC output current in a plurality of stages each May be propagated through the plurality of stages to produce voltage pulses in an inductor (e.g., an output inductor L _OUT ). The flux injector system may be configured to automatically deactivate and reactivate the flux-shuttle loop based on the amplitude of the DC output current with respect to the amplitude of the DC injection signal.

The above are examples. It is, of course, not possible to describe all conceivable combinations of components or methods for purposes of describing the present invention, but one of ordinary skill in the art will recognize that many additional combinations and permutations are possible will be. Accordingly, the invention is intended to embrace all such alterations, modifications and variations that fall within the scope of this application, including the appended claims. In addition, when the present disclosure lists the "one," " first "or" other "elements or the like, it does not preclude or exclude two or more such elements, Should be interpreted as As used herein, the term "include" means include but is not limited to, and the term " including " The term " based on "means at least partially based.

Claims (20)

In the Josephson current question system,
A flux-shuttle loop comprising a plurality of stages arranged in a series loop, each of the plurality of stages comprising at least one Josephson junction, the flux-shuttle loop being activated The at least two of the plurality of stages in each of the plurality of stages about the flux-shuttle loop in response to an inductively coupled AC clock signal to produce a DC output current provided through the output inductor. Configured to sequentially trigger one Josephson junction; And
Shuttle loop and is configured to deactivate the flux-shuttle loop automatically in response to the amplitude of the DC output current increasing to a predetermined deactivation threshold doing,
Josephson current source system. The system of claim 1, wherein the flux injector system comprises:
Shuttle loop in response to an amplitude of the DC output current decreasing to a predetermined activation threshold,
Josephson current source system. The method according to claim 1,
A plurality of storage inductors, each of the plurality of storage inductors coupled to at least one of the plurality of stages and configured to receive a voltage pulse associated with a sequential trigger of the Josephson junction in each of the plurality of stages -; And
Further comprising an output inductor coupled to each of the plurality of storage inductors and configured to provide the DC output current in response to the voltage pulse provided through each of the plurality of storage inductors.
Josephson current source system. The method according to claim 1,
Wherein the flux injector system includes an injection transformer inductively coupled to the flux injector system,
Wherein the injection converter injects a single-flux quantum (SFQ) pulse in response to the DC output current below a predetermined activation threshold and responds to the DC output current greater than the predetermined deactivation threshold And to induce an injection current based on a DC injection signal to inject a negative SFQ pulse.
Josephson current source system. 5. The method of claim 4,
Wherein the flux injector system forms a portion of one of the plurality of stages,
The DC injection signal having a predetermined amplitude defining both the predetermined activation threshold and the predetermined deactivation threshold based on the flux of each stage of the plurality of stages,
Josephson current source system. 5. The method of claim 4,
Wherein the flux injector system further comprises a feedback converter coupled inductively with the flux injector system,
Wherein the feedback converter is configured to derive a feedback current based on the DC output current,
The feedback current having a current direction opposite to the injection current to automatically deactivate and reactivate the flux-shuttle loop based on the amplitude of the feedback current relative to the amplitude of the injection current,
Josephson current source system. The method according to claim 1,
Wherein the AC clock signal comprises an in-phase component and a quadrature-phase component,
Wherein the co-phase component and the quadrature-phase component are phase shifted by about 90 degrees,
Josephson current source system. 8. The method of claim 7,
The plurality of stages comprising a first stage, a second stage, a third stage and a fourth stage arranged in a continuous series loop,
Wherein the first stage and the third stage are coupled to a first clock converter and the second stage and the fourth stage are coupled to a second clock converter,
The first clock converter includes a primary inductor configured to propagate the co-phase component of the AC clock signal,
Wherein the second clock converter includes a primary inductor configured to propagate the quadrature-phase component of the AC clock signal.
Josephson current source system 9. The method of claim 8,
During activation of the flux-shuttle loop,
Wherein the first stage is responsive to a first phase of the co-phase component of the AC clock signal to generate a single flux quantum (SFQ) signal in the second stage based on triggering of each of the at least one Josephson junctions. ) Pulse,
Wherein the second stage is configured to propagate the SFQ pulse to the third stage based on a trigger of each of the at least one Josephson junctions in response to a first phase of the quadrature-phase component of the AC clock signal,
Wherein the third stage is responsive to a second phase of the co-phase component of the AC clock signal opposite to the first phase to apply the SFQ pulse to the fourth stage based on a trigger of each of the at least one Josephson junctions. , ≪ / RTI >
Wherein the fourth stage is responsive to a second phase of the quadrature-phase component of the AC clock signal opposite to the first phase to apply the SFQ pulse to the first stage based on a trigger of each of the at least one Josephson junctions. ≪ / RTI >
Josephson current source system. 10. The method of claim 9,
Wherein the first clock converter includes a secondary inductor arranged in a first loop together with the first stage and the third stage,
The second clock converter includes a secondary inductor arranged in a second loop together with the second stage and the fourth stage,
In the Josephson current source system,
An output inductor configured to provide the DC output current;
A first storage inductor interconnecting the output inductor and the first loop to provide a voltage pulse to the output inductor while the SFQ pulse is propagating through the first stage and the third stage, respectively; And
Further comprising a second storage inductor interconnecting the output inductor and the second loop to provide a voltage pulse to the output inductor while the SFQ pulse propagates through each of the second stage and the fourth stage.
Josephson current source system. A method for generating a DC output current,
Providing an AC clock signal through a primary inductor of a clock converter, the clock converter comprising a secondary inductor arranged in a loop with at least two of the plurality of stages of a flux-shuttle loop, The stages of which are arranged in a series sequential loop; And
Providing a DC injection signal to the flux injector system to produce a single flux quantum (SFQ) pulse at one of the plurality of stages,
The SFQ pulse is propagated through the plurality of stages to produce voltage pulses in an output inductor to generate the DC output current based on a sequential trigger of a Josephson junction in each of the plurality of stages,
Wherein the flux injector system is configured to automatically deactivate and reactivate the flux-shuttle loop based on an amplitude of the DC output current relative to an amplitude of the DC injection signal.
A method for generating a DC output current. 12. The method of claim 11,
Further comprising setting an amplitude of the DC injection signal to set at least one of an inactivation threshold and an activation threshold associated with the amplitude of the DC output current for automatic reactivation and deactivation of the flux-shuttle loop, respectively.
A method for generating a DC output current. 12. The method of claim 11, wherein the flux-
A plurality of storage inductors, each of the plurality of storage inductors coupled to at least one of the plurality of stages and configured to receive a voltage pulse associated with a sequential trigger of the Josephson junction in each of the plurality of stages -; And
Further comprising an output inductor coupled to each of the plurality of storage inductors and configured to provide the DC output current in response to the voltage pulse provided through each of the plurality of storage inductors.
A method for generating a DC output current. 12. The method of claim 11,
Wherein providing the DC injection signal comprises providing the DC injection signal to a primary inductor of an injection converter that is inductively coupled to the flux injector system,
Wherein the injection converter is configured to inject the SFQ pulse into the flux-shuttle loop responsive to the DC output current below a predetermined activation threshold and to inject a negative SFQ pulse in response to the DC output current greater than a predetermined deactivation threshold DC injection < / RTI > signal,
A method for generating a DC output current. 15. The method of claim 14,
Wherein the flux injector system further comprises a feedback converter coupled inductively with the flux injector system,
Wherein the feedback converter is configured to derive a feedback current based on the DC output current,
The feedback current having a current direction opposite to the injection current to automatically deactivate and reactivate the flux-shuttle loop based on the amplitude of the feedback current relative to the amplitude of the injection current,
A method for generating a DC output current. 12. The method of claim 11,
The plurality of stages comprising a first stage, a second stage, a third stage and a fourth stage arranged in a continuous series loop,
Wherein providing the AC clock signal comprises propagating the SFQ pulse through each stage of the first stage, the second stage, the third stage, and the fourth stage in each quarter period of the AC clock signal Phase component and a quadrature-phase component of the AC clock signal, respectively,
Wherein the co-phase component and the quadrature-phase component are phase-shifted by about 90 degrees,
A method for generating a DC output current. In the Josephson current source system,
A flux-shuttle loop comprising a first stage, a second stage, a third stage and a fourth stage arranged in a tandem loop, each of said first stage, said second stage, said third stage and said fourth stage comprising at least Wherein the flux-shuttle loop includes a first Josephson junction that when activated activates the first stage around the flux-shuttle loop in response to an inductively coupled AC clock signal, , The third stage and the fourth stage, wherein the AC clock signal comprises a phase-to-phase component and a phase-to-phase component different by about 90 degrees -;
A first storage inductor coupled to the first stage and the third stage and configured to receive a voltage pulse associated with the sequential trigger of the at least one Josephson junction in the first stage and the third stage, respectively;
A second storage inductor coupled to the second stage and the fourth stage and configured to receive a voltage pulse associated with the sequential trigger of the at least one Josephson junction in the second stage and the fourth stage, respectively;
An output inductor coupled to the first storage inductor and the second storage inductor, respectively, and configured to provide a DC output current in response to the voltage pulse provided through the first storage inductor and the second storage inductor, respectively; And
And a flux injector system configured to activate the flux-shuttle loop, the flux injector system being further configured to automatically deactivate and reactivate the flux-shuttle loop based on the amplitude of the DC output current.
Josephson current source system. 18. The method of claim 17,
Wherein the flux injector system includes an injection converter inductively coupled to the flux injector system,
Wherein the injection converter injects a single-flux quantum (SFQ) pulse in response to the DC output current below a predetermined activation threshold and outputs a negative SFQ pulse in response to the DC output current greater than a predetermined deactivation threshold. To inject an injection current based on a DC injection signal to inject the injection current.
Josephson current source system. 19. The method of claim 18,
Wherein the flux injector system forms a portion of one of the plurality of stages,
The DC injection signal having a predetermined amplitude defining both the predetermined activation threshold and the predetermined deactivation threshold based on the flux of each stage of the plurality of stages,
Josephson current source system. 19. The method of claim 18,
Wherein the flux injector system further comprises a feedback converter coupled inductively with the flux injector system,
Wherein the feedback converter is configured to derive a feedback current based on the DC output current,
The feedback current having a current direction opposite to the injection current to automatically deactivate and reactivate the flux-shuttle loop based on the amplitude of the feedback current relative to the amplitude of the injection current,
Josephson current source system.

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